The end of the NFL lockout and the beginning of the business side of football has been particularly bloody for the Giants, who have informed Shaun O’Hara and Rich Seubert they will be released Thursday, when cuts can become official.

Seubert was the first to arrive Tuesday at Giants headquarters and when he drove away, about an hour later, he did not flash his customary smile.

Seubert, 32, suffered a dislocated kneecap and sustained other injuries to his right leg in the last game of the 2010 season and at this point has not made enough progress for the Giants to consider him a viable option. The team did not believe he could pass their physical examination.

O’Hara, the Giants player representative to the NFL Players Association, spent the entire lockout keeping his teammates informed what was going on with the negotiations and also attended sessions with the owners. On his first day back to work, O’Hara was told he will soon be an ex-Giant.

This is a surprise but shouldn’t be a shock. With the Giants ending the lockout slightly more than $6 million over the newly instituted salary cap of $120 million, veterans are in danger of getting cut.

O’Hara, 34, is coming off surgeries to his right foot and left ankle and Achilles tendon, problems that caused him to miss 10 games last season. O’Hara was scheduled to make $3.45 million in salary for the 2011 season and it has been widely speculated he would have to accept a pay cut in order to stay on the roster.

Seubert was scheduled to make $2.25 million this season and $2.45 million in 2012.

Seubert might be coach Tom Coughlin’s most beloved player on the team. General manager Jerry Reese also is a huge fan of Seubert’s, but the decision-makers determined he wasn’t going to be able to help them. Reese following last season called Seubert “the MVP or our team’’ after he moved to center because of several injuries at that position and performed remarkably well. Coughlin gushed about Seubert’s “heart and soul.’’

Seubert was so solid at center he could have been considered a starting option for this season, if not for the injury that hit him in the regular-season finale, a victory over the Redskins. Seubert dislocated his right kneecap and sustained ligament and tendon damage. He had surgery and has been rehabbing this offseason but was not going to be ready to compete in training camp.

Immediately after the injury, Seubert said, “I’m not going to let an injury end my career’’ but it appears that might be the case.

Now the hard part: Finding someone to start at center. This is clearly the end of the solid offensive line unit that helped carry the Giants to victory in Super Bowl XLII and, when healthy, was considered one of the strongest in the league. Without O’Hara and Seubert, there is no proven center on the roster. Adam Koets, a career backup, is coming off surgery to repair a torn anterior cruciate ligament, an injury he suffered Nov. 7 at Seattle.

Another offensive lineman, Kevin Boothe, is a guard who filled in at center in last season’s finale when Seubert went down. Boothe is a free agent.

It stands to reason the Giants will look hard in free agency to sign a veteran center. O’Hara has been the starting center since 2004. The New Jersey native and Rutgers grad quickly became a fixture not only on the offensive line but as a respected team leader.

Seubert back in 2003 suffered through a gruesome injury when his left leg was shattered and his career was thought to be through. But Seubert, who made the team in 2001as an undrafted free agent from Western Illinois, not only battled back but eventually regained his starting job.

Tackle Shawn Andrews, who played in 13 games and started seven last season, tweeted that he and the team failed to rework the six-year, $32-million contract he signed last year.

Andrews also tweeted that things weren’t over, but that might mean his career more than his time with the Giants.